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Sensors 2014, 14(7), 12585-12597; doi:10.3390/s140712585
Article

Correlation Networks for Identifying Changes in Brain Connectivity during Epileptiform Discharges and Transcranial Magnetic Stimulation

1
, 1,*  and 2
Received: 23 April 2014; in revised form: 7 July 2014 / Accepted: 10 July 2014 / Published: 14 July 2014
(This article belongs to the Special Issue Biomedical Sensors and Systems)
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Abstract: The occurrence of epileptiform discharges (ED) in electroencephalographic (EEG) recordings of patients with epilepsy signifies a change in brain dynamics and particularly brain connectivity. Transcranial magnetic stimulation (TMS) has been recently acknowledged as a non-invasive brain stimulation technique that can be used in focal epilepsy for therapeutic purposes. In this case study, it is investigated whether simple time-domain connectivity measures, namely cross-correlation and partial cross-correlation, can detect alterations in the connectivity structure estimated from selected EEG channels before and during ED, as well as how this changes with the application of TMS. The correlation for each channel pair is computed on non-overlapping windows of 1 s duration forming weighted networks. Further, binary networks are derived by thresholding or statistical significance tests (parametric and randomization tests). The information for the binary networks is summarized by statistical network measures, such as the average degree and the average path length. Alterations of brain connectivity before, during and after ED with or without TMS are identified by statistical analysis of the network measures at each state.
Keywords: transcranial magnetic stimulation (TMS); electroencephalograms; epileptic discharges; cross-correlation; partial cross-correlation; causality networks transcranial magnetic stimulation (TMS); electroencephalograms; epileptic discharges; cross-correlation; partial cross-correlation; causality networks
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Siggiridou, E.; Kugiumtzis, D.; Kimiskidis, V.K. Correlation Networks for Identifying Changes in Brain Connectivity during Epileptiform Discharges and Transcranial Magnetic Stimulation. Sensors 2014, 14, 12585-12597.

AMA Style

Siggiridou E, Kugiumtzis D, Kimiskidis VK. Correlation Networks for Identifying Changes in Brain Connectivity during Epileptiform Discharges and Transcranial Magnetic Stimulation. Sensors. 2014; 14(7):12585-12597.

Chicago/Turabian Style

Siggiridou, Elsa; Kugiumtzis, Dimitris; Kimiskidis, Vasilios K. 2014. "Correlation Networks for Identifying Changes in Brain Connectivity during Epileptiform Discharges and Transcranial Magnetic Stimulation." Sensors 14, no. 7: 12585-12597.



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